Pesticide Table for Curtis' Pearly Mussel and the Pink Mucket Pearly Mussel (on the Black River South of Route 49)

Active Ingredient

Product or Trade Name

Chlorpyrifos on Alfalfa

Lorsban

Chlorpyrifos: all other uses except on Alfalfa, or as a Termiticide

Lorsban, Dursban, Pageant

Benomyl

Benlate, Tersan 1991

Carbaryl

Sevin, Sevimol

Diazinon

Diazinon, D-z-n

Dicofol

Kelthane

Dimethoate

Cygon

Disulfoton

Di-Syston

Malathion

Cythion

Naled

Dibrom

Parathion (ethyl)

Parathion, Paraspray

Phosmet

Imidan

Propiconazole

Tilt, Orbit, Banner

Pyrethrins

Pyrellin, Pyrenone, Pyrethrum, and others

Trichlorfon

Dylox, Proxol

Trade names provided by the University of Missouri Extension Service. For additional information, contact your local University Extension office.

Limitations on Pesticide Use

Product or Trade Name

Limitations

Lorsban

Do not apply 100 yards from the water's edge (ground application) nor 1/4 mile from the water's edge (aerial application) within the shaded area(s) shown on the map.

All other products listed

Do not apply 20 yards from the water's edge (ground application) nor 100 yards from the water's edge (aerial application) within the shaded area(s) shown on the map and 1/2 mile up all streams joining the shaded areas.

Propiconazole (Tilt, Orbit, Banner) is also restricted on the Black River north of Route 49 and the St. Francis River south of Wappapello Dam for the protection of the pink mucket pearly mussel.

Curtis' pearly mussel [Epioblasma florentina curtisi]

Curtis' pearly mussel is a small bivalve mollusk, one of seven clams in the genus Epioblasma that have been federally listed as endangered. Like most listed clams, it is a member of the family Unionidae, probably the most imperiled family of organisms in the world. This species has an oval shell that is usally less than four centimeters (1.5 in) in length, with males being slightly larger than females. In both sexes, the shell color is yellow-brown to light brown, sometimes with fine, evenly spaced rays over most of its length. This mussel is a long-term breeder in which eggs are fertilized in the fall and the larvae are released in the spring. Although the names are similar, this animal is not closely related to Curtus' mussel, also known as the Black clubshell.

This pearly mussel makes its home in transitional zones between swift-flowing streams headwaters and the more leisurely meandering currents, where it buries itself in the stream floor of sand, gravel, cobbles, and boulders. The mussel is often found in shallow waters at depths of to 76 centimeters (30 in). Like all other mollusks, Curtis' pearly mussel requires clear, usilted water to live in, because silt clogs the siphon which the animal uses to strain water for nutrients.

Curtis' pearly mussel has historically existed in scattered locations throughout river basins in southern Missouri and northern Arkansas. Since the mid-1970's, this species has only been found in southeastern Missouri, in the Castor River, Can Creek, and the Little Black River. From 1981 to 1983, out of 140 probable locations on 26 streams, this mussel was only found at six sites. Despite the fact that this animal has been listed as an endangered species since 1976, it is still extremely uncommon and is thought to remain near extinction.

Much of the former range of the Curtis' pearly mussel has been destroyed by the construction of reservoirs, like Lake Taneycomo and Bull Shoals Reservoir. Impoundements like these flood habitat upstream, and cause silt accumulation downstream by drastically reducing the flow of water. Stream channeling, gravel dredging, and poor land management practices have further exacerbated the problems of siltation and chemical runoff.

The immediate goal of recovery for Curtis' pearly mussel is to thwart extinction and to prevent further loss and damage of to the habitat. There is hope to transfer mussels from a viable population to depleted areas, and to produce juveniles by artificial culture to assist the restocking of suitable habitat within its historic range.

Pink mucket pearly mussel [Lampsilis orbiculata]

The Pink mucket pearly mussel has an elliptical shell that is 4 in. long, 2.4 in. wide, and 3 inches high. Young mussels have a yellow to brown shell that is smooth and glossy with green rays and growthmarks, while older specimens are a dull brown. This mussel is a unique long-term breeder in which male pink muckets release sperm in late summer or fall that fertilizes larvae in females which is incubated until the following spring. The Pink mucket pearly mussel inhabits shallow riffles or shoals in areas of gravel, rubbel, or sand substrates that have been swept free of silt by the current. (Silt clogs the siphons in which mussels use to strain water for nutrients.)

In the past, populations of this mussel were found in 25 rivers and tributaries in 11 states. Currently, the Pink mucket is known in 16 rivers and tributaries from 7 states with the greatest concentrations in the Tennessee (TN, AL) and Cumberland (TN, KY) rivers, and in the Osage and Meramec rivers (MO). However, large numbers of this species have never been collected and it has always been considered rare. Smaller populations have been found in the Clinch River (TN), Green River (KY), Kwanawha River (WV), in the Big River, Black and Little Black, Gasconde rivers (MO), and in Current and Spring rivers (AR).

The Pink mucket has declined in range and numbers due to dam and reservoir construction that has changed natural river flow, water temperatures, and oxygen and sediment contents. In addition, heavy loads of silt from strip mining, coal washing, dredging, and logging, along with agricultural runoff have significantly deteriorated water quality essential for mussel reproduction and feeding.

In attempts to restore Pink mucket habitat, the states of Tennessee and Alabama have designated mussel sanctuaries in parts of the Cumberland and Tennessee Rivers and have sucessfully reproduced populations at these locations. Recently, live specimens were discovered in the upper Ohio River where the Pink mucket had not been found for 75 years. Scientists associate this to improved water quality in the area and believe that this species could be similarly reintroduced to areas in which the Pink mucket has been extirpated if water quality is restored.